Thailand is one of the Asian countries hardest hit by the HIV/AIDS epidemic. Before the widespread implementation, beginning in 1999, of programmes to prevent mother-to-child HIV transmission, many children were born with HIV in Thailand. They now reach adolescence thanks to antiretroviral treatments. While some qualitative studies have documented the family situation and the living conditions of these adolescents, the TEEWA (Teens Living With ARV) project has, for the first time, conducted a national quantitative survey among 10% of adolescents aged 12-19 infected with HIV at birth, under antiretroviral treatment, in order to assess their situation and compare it with that of adolescents in the general population. This article presents an original survey approach that takes into account the methodological and ethical issues specific to the situation of a population rendered doubly vulnerable by age and HIV status.